Compact electronic systems that interface with biophysical systems can be suitably sensitive to detect even weak signals of such systems without introducing measurement inaccuracies. Signal weakness can increase the effects of measurement noise and, as such, integrated circuit components that minimize measurement noise can be beneficial. A source of such noise can be irregularities in the physical structure found in certain electronic components. These irregularities can produce unpredictable measurement fluctuations called 1/f or flicker noise. Flicker noise can vary inversely as to the area of a transistor and, as such, can affect electronic interfaces to biophysical systems having highly dense transistor arrays.
Flicker noise can be considered a generic name for fluctuations whose power spectral density scales with frequency as SN(f)∝1/f Flicker noise can come from a number of physical sources, such as from inhomogeneous structures that fluctuate unpredictably over time. In integrated electronics, flicker noise can arise from traps in interfaces between materials, semiconductor dopants, and material defects.
Flicker noise can decrease as the size of an element increases, and the increasing number of individual point defects can reduce or inhibit each other. Integrated electronics can be generally planar, and thus flicker noise power can be inversely proportional to the area (W×L) of a transistor.
Certain applications involving electronic interfaces to biophysical systems can include measuring weak signals with fine spatial resolution, high channel count, and low cost. Yet these can be competing goals, at least in part, because reducing the dimensions of electronic elements can yield higher noise levels, which in turn can impact a wide range of applications, including biochemical assays and sequencing platforms, neural recording arrays, and advanced imagers and particle detector readout arrays.
In these and other applications, large arrays on a fine pitch can be desirable, yet the signals can be weak and thus reduced electronic measurement noise can be desirable. Electronic components can contain a range of structural irregularities such as interface traps, dopant inhomogeneity, and material defects. These irregularities can cause unpredictable electrical fluctuations, such as flicker noise.
Junction Field Effect Transistors (JFETs) can exhibit lower levels of flicker noise than other transistor designs at least in part because of their construction. A JFET can achieve a noise target comparable to that of a Metal Oxide Field Effect Transistor (MOSFET) while occupying an area 20 times as small.
Accordingly, there is an opportunity for improved JFET transistors, including CMOS-integrated JFET transistors that can be suitable for dense and low-noise bioelectronic platforms.